/*! Respond.js v1.1.0: min/max-width media query polyfill. (c) Scott Jehl. MIT/GPLv2 Lic. j.mp/respondjs  */
(function( win ){

  "use strict";

  //exposed namespace
  var respond = {};
  win.respond = respond;

  //define update even in native-mq-supporting browsers, to avoid errors
  respond.update = function(){};

  //expose media query support flag for external use
  respond.mediaQueriesSupported	= win.matchMedia && win.matchMedia( "only all" ).matches;

  //if media queries are supported, exit here
  if( respond.mediaQueriesSupported ){
    return;
  }

  //define vars
  var doc = win.document,
    docElem = doc.documentElement,
    mediastyles = [],
    rules = [],
    appendedEls = [],
    parsedSheets = {},
    resizeThrottle = 30,
    head = doc.getElementsByTagName( "head" )[0] || docElem,
    base = doc.getElementsByTagName( "base" )[0],
    links = head.getElementsByTagName( "link" ),
    requestQueue = [],

  //loop stylesheets, send text content to translate
    ripCSS = function(){

      for( var i = 0; i < links.length; i++ ){
        var sheet = links[ i ],
          href = sheet.href,
          media = sheet.media,
          isCSS = sheet.rel && sheet.rel.toLowerCase() === "stylesheet";

        //only links plz and prevent re-parsing
        if( !!href && isCSS && !parsedSheets[ href ] ){
          // selectivizr exposes css through the rawCssText expando
          if (sheet.styleSheet && sheet.styleSheet.rawCssText) {
            translate( sheet.styleSheet.rawCssText, href, media );
            parsedSheets[ href ] = true;
          } else {
            if( (!/^([a-zA-Z:]*\/\/)/.test( href ) && !base) ||
              href.replace( RegExp.$1, "" ).split( "/" )[0] === win.location.host ){
              requestQueue.push( {
                href: href,
                media: media
              } );
            }
          }
        }
      }
      makeRequests();
    },

  //recurse through request queue, get css text
    makeRequests	= function(){
      if( requestQueue.length ){
        var thisRequest = requestQueue.shift();

        ajax( thisRequest.href, function( styles ){
          translate( styles, thisRequest.href, thisRequest.media );
          parsedSheets[ thisRequest.href ] = true;

          // by wrapping recursive function call in setTimeout
          // we prevent "Stack overflow" error in IE7
          win.setTimeout(function(){ makeRequests(); },0);
        } );
      }
    },

  //find media blocks in css text, convert to style blocks
    translate = function( styles, href, media ){
      var qs = styles.match(  /@media[^\{]+\{([^\{\}]*\{[^\}\{]*\})+/gi ),
        ql = qs && qs.length || 0;

      //try to get CSS path
      href = href.substring( 0, href.lastIndexOf( "/" ) );

      var repUrls	= function( css ){
          return css.replace( /(url\()['"]?([^\/\)'"][^:\)'"]+)['"]?(\))/g, "$1" + href + "$2$3" );
        },
        useMedia = !ql && media;

      //if path exists, tack on trailing slash
      if( href.length ){ href += "/"; }

      //if no internal queries exist, but media attr does, use that
      //note: this currently lacks support for situations where a media attr is specified on a link AND
      //its associated stylesheet has internal CSS media queries.
      //In those cases, the media attribute will currently be ignored.
      if( useMedia ){
        ql = 1;
      }

      for( var i = 0; i < ql; i++ ){
        var fullq, thisq, eachq, eql;

        //media attr
        if( useMedia ){
          fullq = media;
          rules.push( repUrls( styles ) );
        }
        //parse for styles
        else{
          fullq = qs[ i ].match( /@media *([^\{]+)\{([\S\s]+?)$/ ) && RegExp.$1;
          rules.push( RegExp.$2 && repUrls( RegExp.$2 ) );
        }

        eachq = fullq.split( "," );
        eql	= eachq.length;

        for( var j = 0; j < eql; j++ ){
          thisq = eachq[ j ];
          mediastyles.push( {
            media : thisq.split( "(" )[ 0 ].match( /(only\s+)?([a-zA-Z]+)\s?/ ) && RegExp.$2 || "all",
            rules : rules.length - 1,
            hasquery : thisq.indexOf("(") > -1,
            minw : thisq.match( /\(\s*min\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/ ) && parseFloat( RegExp.$1 ) + ( RegExp.$2 || "" ),
            maxw : thisq.match( /\(\s*max\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/ ) && parseFloat( RegExp.$1 ) + ( RegExp.$2 || "" )
          } );
        }
      }

      applyMedia();
    },

    lastCall,

    resizeDefer,

  // returns the value of 1em in pixels
    getEmValue = function() {
      var ret,
        div = doc.createElement('div'),
        body = doc.body,
        fakeUsed = false;

      div.style.cssText = "position:absolute;font-size:1em;width:1em";

      if( !body ){
        body = fakeUsed = doc.createElement( "body" );
        body.style.background = "none";
      }

      body.appendChild( div );

      docElem.insertBefore( body, docElem.firstChild );

      ret = div.offsetWidth;

      if( fakeUsed ){
        docElem.removeChild( body );
      }
      else {
        body.removeChild( div );
      }

      //also update eminpx before returning
      ret = eminpx = parseFloat(ret);

      return ret;
    },

  //cached container for 1em value, populated the first time it's needed
    eminpx,

  //enable/disable styles
    applyMedia = function( fromResize ){
      var name = "clientWidth",
        docElemProp = docElem[ name ],
        currWidth = doc.compatMode === "CSS1Compat" && docElemProp || doc.body[ name ] || docElemProp,
        styleBlocks	= {},
        lastLink = links[ links.length-1 ],
        now = (new Date()).getTime();

      //throttle resize calls
      if( fromResize && lastCall && now - lastCall < resizeThrottle ){
        win.clearTimeout( resizeDefer );
        resizeDefer = win.setTimeout( applyMedia, resizeThrottle );
        return;
      }
      else {
        lastCall = now;
      }

      for( var i in mediastyles ){
        if( mediastyles.hasOwnProperty( i ) ){
          var thisstyle = mediastyles[ i ],
            min = thisstyle.minw,
            max = thisstyle.maxw,
            minnull = min === null,
            maxnull = max === null,
            em = "em";

          if( !!min ){
            min = parseFloat( min ) * ( min.indexOf( em ) > -1 ? ( eminpx || getEmValue() ) : 1 );
          }
          if( !!max ){
            max = parseFloat( max ) * ( max.indexOf( em ) > -1 ? ( eminpx || getEmValue() ) : 1 );
          }

          // if there's no media query at all (the () part), or min or max is not null, and if either is present, they're true
          if( !thisstyle.hasquery || ( !minnull || !maxnull ) && ( minnull || currWidth >= min ) && ( maxnull || currWidth <= max ) ){
            if( !styleBlocks[ thisstyle.media ] ){
              styleBlocks[ thisstyle.media ] = [];
            }
            styleBlocks[ thisstyle.media ].push( rules[ thisstyle.rules ] );
          }
        }
      }

      //remove any existing respond style element(s)
      for( var j in appendedEls ){
        if( appendedEls.hasOwnProperty( j ) ){
          if( appendedEls[ j ] && appendedEls[ j ].parentNode === head ){
            head.removeChild( appendedEls[ j ] );
          }
        }
      }

      //inject active styles, grouped by media type
      for( var k in styleBlocks ){
        if( styleBlocks.hasOwnProperty( k ) ){
          var ss = doc.createElement( "style" ),
            css = styleBlocks[ k ].join( "\n" );

          ss.type = "text/css";
          ss.media = k;

          //originally, ss was appended to a documentFragment and sheets were appended in bulk.
          //this caused crashes in IE in a number of circumstances, such as when the HTML element had a bg image set, so appending beforehand seems best. Thanks to @dvelyk for the initial research on this one!
          head.insertBefore( ss, lastLink.nextSibling );

          if ( ss.styleSheet ){
            ss.styleSheet.cssText = css;
          }
          else {
            ss.appendChild( doc.createTextNode( css ) );
          }

          //push to appendedEls to track for later removal
          appendedEls.push( ss );
        }
      }
    },
  //tweaked Ajax functions from Quirksmode
    ajax = function( url, callback ) {
      var req = xmlHttp();
      if (!req){
        return;
      }
      req.open( "GET", url, true );
      req.onreadystatechange = function () {
        if ( req.readyState !== 4 || req.status !== 200 && req.status !== 304 ){
          return;
        }
        callback( req.responseText );
      };
      if ( req.readyState === 4 ){
        return;
      }
      req.send( null );
    },
  //define ajax obj
    xmlHttp = (function() {
      var xmlhttpmethod = false;
      try {
        xmlhttpmethod = new win.XMLHttpRequest();
      }
      catch( e ){
        xmlhttpmethod = new win.ActiveXObject( "Microsoft.XMLHTTP" );
      }
      return function(){
        return xmlhttpmethod;
      };
    })();

  //translate CSS
  ripCSS();

  //expose update for re-running respond later on
  respond.update = ripCSS;

  //adjust on resize
  function callMedia(){
    applyMedia( true );
  }
  if( win.addEventListener ){
    win.addEventListener( "resize", callMedia, false );
  }
  else if( win.attachEvent ){
    win.attachEvent( "onresize", callMedia );
  }
})(this);
